1. Field of the Invention
The present invention relates to a liquid crystal display, and more particularly, to a liquid crystal display that has an improved display performance (image appearance) by reducing the reflection factor of lead-out wiring.
2. Description of the Related Art
In order to address recent trends toward the miniaturization and cost-reduction of electronic devices, a STN (Super-Twisted Nematic) liquid crystal display in which two driving ICs are combined into a single driving IC, is in use. Specifically, in this type of liquid crystal display, the driving ICs that were connected to the conventional transparent electrodes on the common side and segment side are replaced by a single driving IC located on only one side surface of a panel.
In such a liquid crystal display, a terminal portion is formed on one substrate out of a pair of substrates between which a liquid crystal layer is sandwiched. Each of the transparent electrodes on the common side and segment side must be connected to this terminal portion, and the terminal portion and each of the transparent electrodes have hitherto been connected by forming lead-out wiring of a transparent conductive material such as ITO (Indium Tin Oxide).
In recent liquid crystal displays, a time-division multiplex system has been adopted to drive the display. Further, the liquid crystal display is driven using multi-gradation control, and therefore, the deviation of the driving voltage must be minimized. However, when the lead-out wiring is formed of ITO or similar materials, which have a relatively high specific resistance, reduction in the deviation of the driving voltage is difficult to obtain. This causes uneven display such that the display in a display area at a relatively far distance from the terminal portion becomes paler in color. In particular, depending on the length of the lead-out wiring, the resistance of the lead-out wiring itself might become as high as a dozen or so mega ohms (MΩ), which is comparable to the resistance value of an electrical insulator. Such a large resistance makes it extremely difficult to drive the liquid crystal display.
On the other hand, when the width of the lead-out wiring is increased to decrease the resistance of the wiring, the area from the display area, which is the forming area of the lead-out wiring, up to the product outer shape portion (the area other than the display area) may disadvantageously increase.
Accordingly, in recent years, a technique is under development that improves the conductivity of the transparent electrodes by providing a metal film along each of the transparent electrodes on the common side and segment side. By increasing the conductivity of the wiring, uneven display may be prevented and the forming area of the lead-out wiring may be reduced.
However, when a metal film is provided along each of the transparent electrodes, the amount of reflected light increases because of a high reflection factor of the metal film. Particularly in reflection-type liquid crystal displays, this poses a problem in that the display performance thereof degrades under the influence of reflected light.